The achievements of the bicyclist over any particular course or track are limited by his form and style, by his personal physical characteristics and by the characteristics of his bicycle. The weight of the bicycle has long been recognized as an important factor in the performance equation, and high performance bicycles are generally designed to have the minimum weight consistent with the required size and strength. The conventional "diamond" bicycle frame, in use for many years, has been intensively studied for the purpose of weight reduction to make possible light weight steel frames having the strength and rigidity to support the rider as the wheels roll over surfaces which may be rough or uneven, and to transmit the forces of pedaling, steering and braking. Each high performance frame design is the product of compromises based on the weight and structural characteristics of a particular metal or alloy, and of the diameter and wall thickness of the tubes making up the frame. A high quality, light weight alloy steel frame in the standard size range will generally weigh at least 6 to 7 pounds, and all efforts to achieve further weight reduction collide head-on with the fact that lighter frames are prone, in vigorous use, to bend beyond the elastic limits of their component tubes and to be permanently deformed. Such deformation usually renders the bicycle useless for its intended purpose and may make it dangerous to use under the stress of competition riding.
Previous bicycle enthusiasts have explored the possibilities of making frames out of materials other than steel, and frames of light weight, high strength metal such as titanium have been built. Titanium, at 0.16 lb/cu.in. weighs 45% less than steel at 0.28 lb/cu.in. and has a considerably higher strength to weight ratio. While titanium metal is, pound for pound, appreciably stronger than steel, it is also much more flexible. The tubes of which titanium bicycle frames have been fashioned have a lower modulus in bending than steel tubes, with the result that the frames have tended to be overly flexible or "whippy" under the stress of vigorous riding. In order to stiffen the titanium frames to make the bicycle more ridable, designers have increased the diameters and/or wall thickness of the titanium tubes. However, this approach results in the addition of titanium metal which is not otherwise required for the strength of the frame, reduces the weight advantage which is the sole reason for using titanium in the first place, and still does not provide the desired riding characteristics.
For the foregoing reasons, it is desirable to provide means for reducing the flexibility of a titanium bicycle frame without adding appreciably to the minimum weight of the metal required for the basic strength of the frame.